Roasting-furnace.



J. E. GREENAWALT. ROASTING FURNACE.

APPLICATION FILED DBO. 27, 1901.

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ROASTING FURNACE.

APPLICATION FILED D30. 27, 1901.

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JQHN E. -GREENAWALT, .OF DENVER, COLORADO.

' ses m emes- To all whom it may concern:

B .e it known that I, J OHN Ii GREENAWALT, a-eltizen of the United States of America, resldlng Denver, in the county of Arapahoe and State of Colorado, have invented certain new and useful Improvements in Roast ng-Furnaces; and I do declare the follow ng to be a full, clear, and exact descriptron of the invention, such as willenable oth rs Skilled in the art to which it appertains to make and use the same, reference be ng bad to the accompanying drawings, and to the figures of reference marked thereon, which form a part of thisspecification.

My invention relates to improvements in roasting furnaces.

ore is generally moved into the hi The object of these improvements is to ,ehmmate the mechanical and metallurgical difliculties encountered in fur ces as at.

present constructed for the preparation of ores for the extraction of their values by a hemi l s -ut he roasting operation forms a very important factor in the successful extraction of the precious metals from theire-ores by means of a chemical solution; the object sought being to leave the precious metals in a condition to be actedupon by the solvent and to put the baser metals and elements in a condition to resist the action of the solvent. To do this properly requires an abundant supply of oxygen in order to thorou hly oxidize all the oxidizable elements efore subjectin the ore to the high temperature required y some of the base elements to resist the gold dissolving solution. These improvements apply especially to the mechanical type of reverberating furnace. The principal difficulties of this type of furnace as heretofore constructed are encountered in connection with the air supply, and the continuous operation of the rabbles. In such furnaces the only means of supplying air is at the upper surface of the ore and this is so slow and imperfect that the hly heated region of the furnace before a the comb tih le elements have been oxidized; the result is that some of the mineral particles become cindered and fused, thus preventa high percentage of extraction of the as d silver. I have determined that all f the on bu t b e lement o t we can be h r e dized at a mp at ve y low temperature when the ore issupplied an ab ndan e 0t pur a r, nd that the Specification of Letters Patent. Application filed December 27, 1901. Serial No. 87,610.

detail reference being struction of this furnace I Patented 20, 1909.

oxidized mineral particles areleft open and porous; also, that the capacity of the furnace is largely increased. I have also determined that in the mechanical operation of a reverberator roasting furnace, .there is practically no di%cul ty wlth the operating mechanism passing through the furnace, so long as the chains and rabbles are properly cooled and the track located within the furnace itself maintains its original shape and position. In order to accomplish this and prevent the track from acquiring the high temperature of. the furnace, I subject the sur-' faces of the track opposite those exposed to the heat to a coohng influence either by means of atmospheric air or water. The operating .chain and trucks will withstand the high heat of the furnace as well as the rabbles proper, so that I pass these throu h the furnace itself, simply separating t e trackfrorn the ore by means of a. fire clay tile.

The invention will now be described in made to the accompanying drawing in which, Figure 1 represents a cross sect on of the furnace. Fig. 2 is a section taken lengthwise of the furnace, the parts being shown on a smaller scale. Fig. 3 shows an important modification of the invention.

In Fig. 1 of the drawing is shown the method 0f introducing the air to the ore throughthe orous hearth, also the manner of cooling e rabble tracks. In the conprefer to build a solid hearth for the furnace and construct this hearth of concrete with a layer of strong cement for a finishing coating, leaving a space of about nine inches between this hearth proper and the lowest point of the rabble plows. This space, which extends ahnost the entire length of the furnace, I divide into sections approximately square by solid walls reachin nearly to the lowest point of the rabbles; t e object of this wall being to prevent the air introduced into one section from esca ing into the fidJOlIllIlg section. The divi mg of this space between the hearth and the rabble plows into sections is necessary to control the amount of a r delivered to the ore at the various stages ,of the roastill Op ration. J At the side of lesfd the f h Th o. c nt r a. fees .j tlo e j hing this onduit iste. them i of the furnace'acceasible fonrepairs, etc. In

p t-he space between the rabbles I above them and so on until the last four inches which consists of ore as fine as that which is to be roasted and from which the intensly fine dust has beenscreened. Upon this filter the ore rests in its passage through the furnace, the rabbles passing over the ,on a sand filter.

terial, such as fine sand, mineral wool, fibrous filter and moving the ore ahead at regular intervals. The air and steam, when it is desirable to use steam in the roasting opera tion are passed under pressure from the main pipes 9 and'17 to a branch pipe 10 into the conduit 5 of each section and thence to the hearth. The large spaces among the coarse ore, permit the air to quickly and evenly distrlbute itself over the hearth and then filter or percolate' uniformly through the interstices between the fine ore particles; the idea being not to create a blast of air, but to simply have a light pressure and force the air through the pores of the filter without disturbing the porous filter or the ore particles. The action is analogous to water percolating through ore placed This construction can also be used to introduce chlorin or other gaseous products into the ore mass during its passage-through the furnace. While I prefer ore for the construction of this filter, it is evident that any suitable fine porous maasbestos, etc., supporting the weight of the ore 1n'1ts passage through the furnace, with means to conduct air through it into the ore mass, would answer the purpose. However, low grade ore similar'to that regularly treated is far preferable, since it is easy to get and place into position and in .case any of the precious-metals find their way into the filter, it can be removed and given the regular treatment for the extraction of whatever values it may contain. The tracks 14 upon which the truck wheels 13 of the rabbles run, are made of hollow cast iron, the interior of which is sealed from the furnace, and arranged for cooling either by air or water, preferably by water indirectly by placing a pipe 15 filled with water into it.

' water pipe will keep'the casting suf- \.-fic1ently pool to maintain its original po- Trace where the rabbles and on their return journey.

sition and condition. The hollow cast iron track also has a flange 14 to receive the tile artition 16 separating the ore from the track, so that it will always retain its position relatively to the track.

In F1 2 are shown the s rocket wheels 21 and 2 over which the chalns and rabbles travel, and also the track 22 above thefurchains are cooled This section also shows the porous hearth and the walls 23 dividing the: porous hearth into sections, so

livered to the ore mass that varying quantities of the air can be deduring its travel through the furnace.

The feeding of the ore to the furnacehearth I accomplish as follows: In the ore bin 24, I place an adjustable gate 25 which can be raised or lowered, thus raising or lowering the surface of the ore mass as it comes from the bin. The ore in the bin being fine and perfectly dry always assumes approximately the same angle, and by raising or lowering the gates, the rabbles cut into the ore to a greater or less extent and consequently the amount of ore fed into the furnace can be varied as desired. The shaft 26 carrying the rear sprocket wheels 27 is mounted on adjustable take up boxes the adjustment being effected by screws'28. The

chains used ordinarily for this purpose are quite heavy and there is considerable sag in the chain between the rabbles, so that the shaft 26 can be moved backward 01' forward considerably without interfering with the operation of the chain or rabbles; consequently by means of the screws 28 the rabbl'es can be made to cut into the ore to a greater or less extent and the amount of ore fed into the furnace governed accordingly.

I prefer to heat the furnace with producer gas which I introduce at 29 (see Fig. 2) permitting it to flow over the hot roasted ore before it is withdrawn from the pit or hopper 30. It passes through the opening 31 into the furnace.

,Fig. 3 shows a track 14 constructed with its interior exposed to the atmosphere so that it is accessible from the outside; it also shows the manner of constructing the porous hearth for hand furnaces where hoes or hand rakes are used to stir the ore. In this case there is a space of about one inch left between the bricks of the hearth and this space is filled with porous material and supplied with air. brickdiminishes the porous area considerably, yet. it is necessary in order to protect the porous material from the hoe or rake of the workmen in hand furnaces. This construction is also'adapted for use with the power operated rabbles or the mechanical stirrers shown in this and the other views.

. Having thus described my invention, what I claim 1s:

1. In a reverberatory roasting furnace, the combination with a hearth proper, of a porous filter or mass supporting the weightof the ore in its passage through the furnace,

and located between the hearth proper and the line of travel of the lowest point of the rabbles, a rabble for conveying the ore through the furnace and over the porous filter, and means for passing. air or other gases through the porous filter to the ore mass above. p

2. In a reverberatory roasting furnace, the

combination of a porous hearth supporting the ore in its passage through the furnace, a rabble for working the ore through. the furnace and over the porous hearth, and means for delivering air or gases to the porous hearth whereby it is caused to pass throu h the pores or interstices of the hearthto t e ore mass.

3. In a roasting furnace, the combination of a porous hearth supporting'the ore to be treated, and means for passing air or gases through the porous hearth to the ore mass.

4. In a reverberatory furnace, the combination of porous material for supporting the ore, an air chamber or passage underneath said porous material, and means for introducing'air or other gases to said chamber or passage.

5. In a reverberatory furnace, the combination of a porous hearth supporting the ore to be'treated, a' conduit through which said porous hearth may be replaced or removed,

and means for supplying air to pass beneath the. hearth, substantially as described and for the purpose set forth.

6. In a reverberatory roasting furnace, the combination of a porous hearth'supporting the weight of the ore, means for supplying air through the porous hearth to the ore, and.

partitions ,dividing the porous hearth into sections, substantially as described.

7. In a reverberatory furnace, the combination with a suitable hearth and rabbles, of a hollow track for the wheels of the rabbles, and a conduit located within thev hollow of the track for passin a cooling liquid therethrough, substantial y as described.

8. In a reverberatory furnace, the combination with a suitable hearth and rabbles, of a hollow track for the wheels of the rabbles,

said track being open on one end to permit adapted and applied for preventing the ore from falling through the said apertures.

11. An ore roasting furnace comprising a hearth structure composed of superimposed layers, the upper layer being provided with apertures of definite size 'and'ilocation, and

means for passing air upwardly through with apertures of definite or appreciable size, porous material adapted and applied for preventing the load carried by the sa1d apertures, and means for forcing a fluid treating agent upwardly through the said porous material and apertures and into the said load on the hearth or be hearth or bed from falling through the said 14. A furnace for treating materials, comprising a hearth or bed composed of hard material provided with apertures of definlte or appreciable size, porous means adapted and applied for preventing the materials carried on the hearth or bed from falling through the said apertures, and means for forcing a fluid treating agent throughthe said porous material and apertures and lnto the materials on the said hearth or bed.

15. A roasting furnace for roasting gold ore, or other ores, comprising a hearth or bed made of hard material and rovided with a smooth and flat upper sur ace, said hearth or bed having apertures of definite or appreciable size, suitable means for pre- I venting the pulverized ore, or other materials, carried by the hearth or bed, from falling through the said apertures, and means for introducing air upwardly through said apertures and into the body of ore or othler material carried by the said hearth or ed.-

16. An ore roasting furnace comprisin a hearth provided with pockets, means or passing air upwardly through said pockets, mechanical rabbles, arranged above said hearth, and porous means adapted and ap,-

plied for preventing the ore from falling through sa1d pockets.

,In testimonfy whereof I aflix my signature in presence 0 two witnesses.

JOHN E. GREENAWALT, Witnesses:

Dana NELSON, A. J. OBRmN. 

